docs: def _slice(self, start, end):
          """Used internally to get a slice, without error checking."""
          if end == start:
              return self.__class__()
          offset = self._offset
          startbyte, newoffset = divmod(start + offset, 8)
          endbyte = (end + offset - 1) // 8
          bs = self.__class__()
          bs._setbytes_unsafe(self._datastore.getbyteslice(startbyte, endbyte + 1), end - start, newoffset)
          return bs